Methods and systems for blood speckle imaging

ABSTRACT

The systems and methods generally relate to blood speckle imaging. The systems and methods transmit a plurality of transmit (Tx) beams from an ultrasound probe to a region of interest (ROI). The plurality of Tx beams are transmitted successively with respect to each other. At least two of the plurality of Tx beams overlap at a common position. The systems and methods estimate velocity fields from the speckle tracking, and weight the velocity fields based on weighting signals to form weighted velocity fields. The weighting signal being centered at transmit beam axes of the plurality of Tx beams. The systems and methods interpolate the weighted velocity fields that overlap at the common position to adjust a portion of the weighted velocity fields, and generate an image on a display of a combined velocity field by combining the weighted velocity fields.

FIELD

Embodiments described herein generally relate to blood speckle imaging.

BACKGROUND OF THE INVENTION

During an ultrasound exam, a velocity field is estimated by performingspeckle tracking between repeated acquisitions performed by aconventional ultrasound imaging system. The speckle tracking detectsmotion between successive clutter filtered B-mode frames of ultrasounddata. The B-mode frames need to be acquired repeatedly in succession inorder to detect the speckle pattern displacement over time. Moreover aregion of interest (ROI) may typically have to be subdivided intoseveral adjacent subsections where such a displacement detection byrepeated firing is performed in succession from one side of the ROI tothe other. This method for detecting the velocity field for the entireROI has the inherent problem that since the recording and detection mustoccur with a delay between different subsections of the ROI, thevelocity field estimated in the ultrasound exam will be laterallycomposed of subsections recorded at slightly different instances,between which there are time gaps. The time gaps represent borders oftwo such subsections, corresponding to different transmit beamdirections of an ultrasound probe. Each subsection will be composed ofdata from a number of parallel receive beams or MLAs that representssimultaneously acquired data from one transmit direction, repeated apredefined number of times, that covers the area of the subsection. Thespeckle pattern set up by the moving particles will be uncorrelatedbetween two subsections due to this time difference. Hence for particlesclose to the borders of a subsection it is not known from where theycame or to where they are going. Even though the velocity of theparticles is more slowly varying than the patterns and hence is morecorrelated from subsection to subsection, estimates of the velocityfield at the time gaps represent discontinuities of the motion for thespeckle tracking. Moreover the lack of good estimate at the border isforming a gray zone. The gray zone represents a portion of theultrasound image where the velocity field is not known.

For example, the motion in the region of interest can be detected onlyat certain positions during a finite time interval. A velocity atpositions along an edge of the subsection covered by one transmitdirection or scan of the ultrasound imaging system cannot be estimated.The positions along the edge represent points whose lateral movementsare not known and form the gray zone.

BRIEF DESCRIPTION OF THE INVENTION

In an embodiment a method (e.g, for speckle tracking) is provided. Themethod includes transmitting a plurality of transmit (Tx) beams from anultrasound probe to a region of interest (ROI). The plurality of Txbeams are transmitted successively with respect to each other. Theplurality of Tx beams are configured to acquire ultrasound data forspeckle tracking by repeatedly firing along the Tx beams. At least twoof the plurality of Tx beams overlap at a common position. The methodincludes estimating velocity fields from the speckle tracking andweighting the velocity fields based on weighting signals to formweighted velocity fields. The weighting signal being centered attransmit beam axes of the plurality of Tx beams. The method includesinterpolating the weighted velocity fields that overlap at the commonposition to adjust a portion of the weighted velocity fields The methodincludes generating an image of a combined velocity field on a displayby combining the weighted velocity fields.

In an embodiment a system (e.g., a medical imaging system) is provided.The system includes an ultrasound probe configured to acquire ultrasounddata for speckle tracking, a display, and a controller circuit. Thecontroller circuit is configured to instruct the ultrasound probe totransmit a plurality of transmit (Tx) beams to a region of interest(ROI). The plurality of Tx beams are transmitted successively withrespect to each other. The plurality of Tx beams are configured toacquire ultrasound data for speckle tracking by repeatedly firing alongthe Tx beams. At least two of the plurality of Tx beams overlap at acommon position. The controller circuit is configured to estimatevelocity fields from the speckle tracking and weight the velocity fieldsbased on weighting signals to form weighted velocity fields. Theweighting signal being centered at transmit beam axes of the pluralityof Tx beams. The controller circuit is configured to interpolate theweighted velocity fields that overlap at the common position to adjust aportion of the weighted velocity fields The controller circuit isconfigured to generate an image of a combined velocity field on thedisplay by combining the weighted velocity fields.

In an embodiment a method (e.g, for speckle tracking) is provided. Themethod includes transmitting a plurality of transmit (Tx) beams from anultrasound probe to a region of interest (ROI). The plurality of Txbeams are transmitted successively with respect to each other. Theplurality of Tx beams are configured to acquire ultrasound data forspeckle tracking by repeatedly firing the plurality of Tx beams. Atleast two of the plurality of Tx beams overlap at a common position. Themethod includes weighting the velocity fields estimated from ultrasounddata based on weighting signals to form weighted velocity fieldsestimated from ultrasound data. The weighting signal being centered attransmit beam axes of the plurality of Tx beams. The method includesidentifying non-collinear ultrasound data from the ultrasound data, andgenerating at least one sub-image from the non-collinear ultrasounddata. The method also includes weighting and interpolating velocityfields estimated from ultrasound data recorded along receive lines thatare non-collinear between the sub-images as long as the spatial regionthe lines cover overlap. The velocity values at corresponding points inthe sub-images within the overlap region may be estimated from knowledgeof the velocity field and subsequently be interpolated between thesub-images. The method includes interpolating the weighted velocityfields derived from ultrasound data that overlap at the common position.The velocity field includes at least two sectors and represent a twodimensional blood velocity of the ROI. At least one of the velocityfields is estimated based on interpolating the ultrasound data of the atleast one sub-image with a portion of the weighted ultrasound data. Themethod includes generating a smooth velocity field visualization on adisplay by combining the velocity fields.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic block diagram of an embodiment of amedical imaging system.

FIG. 2A illustrates an embodiment of a scan region.

FIG. 2B illustrates an embodiment of acquisition frames of a region ofinterest.

FIG. 3 illustrates an embodiment of a registration model and ultrasounddata of a receive line.

FIG. 4 illustrates an embodiment of a weighting signal relative toreceive lines.

FIG. 5 illustrates an embodiment of velocity data based on a pair ofacquisition frames.

FIG. 6 illustrates an embodiment of velocity fields based on acquisitionframes.

FIG. 7 illustrates a flow chart of an embodiment of a method for speckleimaging.

FIGS. 8 illustrate an embodiment of at least one sub-image based onnon-collinear ultrasound data.

FIG. 9 illustrates an embodiment of an ultrasound image shown on adisplay.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description of certain embodiments will be betterunderstood when read in conjunction with the appended drawings. To theextent that the figures illustrate diagrams of the functional modules ofvarious embodiments, the functional blocks are not necessarilyindicative of the division between hardware circuitry. Thus, forexample, one or more of the functional blocks (e.g., processors ormemories) may be implemented in a single piece of hardware (e.g., ageneral purpose signal processor or a block of random access memory,hard disk, or the like). Similarly, the programs may be stand-aloneprograms, may be incorporated as subroutines in an operating system, maybe functions in an installed software package, and the like. It shouldbe understood that the various embodiments are not limited to thearrangements and instrumentality shown in the drawings.

As used herein, an element or step recited in the singular and proceededwith the word “a” or “an” should be understood as not excluding pluralof said elements or steps, unless such exclusion is explicitly stated.Furthermore, references to “one embodiment” of the present invention arenot intended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features. Moreover, unlessexplicitly stated to the contrary, embodiments “comprising” or “having”an element or a plurality of elements having a particular property mayinclude additional elements not having that property.

Various embodiments described herein generally relate to speckleimaging. A medical imaging system directs a plurality of successivetransmissions from an ultrasound probe. The successive transmissions areutilized in connection with multiple line acquisitions (MLA) and/orparallel receive lines. The MLA is utilized to acquire ultrasound datato form a sub section of the entire image with a certain lateralextension covering the transmit beam. Repeated acquisitions of the sametransmit direction in the course of this succession may be used tospeckle track the ultrasound pattern over time and estimate a velocityfield. The velocity field represents a two dimensional (2D) measurementof blood velocity and/or motion across a region of interest (ROI). Thesuccessive transmissions in the different directions partially overlapat one or more common positions within the ROI. For example, the medicalimaging system configures the MLA beam layout such that receive linesfor at least one transmit beam overlap with a spatially coincidentalreceive line from one or more successive transmit beams. Additionally,the layout of the MLAs are defined such that velocity data is collectedfor at least one transmit event at any given point avoiding gray zones.The ultrasound data of a group of MLAs in the scan plane of theultrasound probe allows overlap with data from the interior of anotherbeam of the MLA. This allows the estimation of the velocity field at thesame spatial location for two or more individual MLA groups recorded atdifferent times. Interpolation may be performed between these estimatesof the velocity at a particular location to prevent discontinuities inthe velocity field from appearing at transitions between the MLA groupsand allows a spatially smooth and continuous field to be displayed.

The partial overlapping of the successive transmissions of the MLA groupallows an interpolation of the velocity field at the one or more commonpositions. For example, the medical imaging system is configured tointerpolate in time the velocity field between successive time instancesacross a time scale of the scan acquisition so that a continuous smoothoutput field of the speckle image can be displayed.

Additionally or alternatively, the medical imaging system is configuredto shift the receive lines. For example, the receive lines of differentMLAs position along common positions can be affected by differences inarrival times for the transmitted wavefront at the particularorientation of the MLA with respect to the transmit beam axis. Themedical imaging system is configured to radially shift the receive linesrepresenting the common location to compensate differences in transmitwavefront arrival time such that the received lines are aligned witheach other.

A technical effect of at least one embodiment described herein enables asmooth velocity field to be generated. A technical effect of at leastone embodiment described herein provides a speckle tracking image withless artifacts and errors visible to the user.

Terms

The term “ultrasound exam” refers to an acquisition of one or moreultrasound images of one or more anatomical structures. The ultrasoundexam can represent a continuous and/or discontinuous acquisition of oneor more ultrasound images (e.g., 2D, 3D, 4D) during a scan of a patient.The scan of the patient may last up to a minute and/or an hour.Optionally, the ultrasound exam can be based on one or more protocols.

The term “collinear ultrasound data” is used to refer to ultrasound datacollected along at least two receive lines that are associated withsuccessive ultrasound transmit signals and that correspond to a commonphysical position.

The term “non-collinear ultrasound data” is used to refer to ultrasounddata collected along at least two receive lines associated withsuccessive ultrasound transmit signals and that correspond to differentpositions.

The term “real time” or “real-time” is used to refer to an operation,action, and/or process performed by the medical imaging system (e.g., acontroller circuit) during an ultrasound exam. An ultrasound exam mayinclude collection of multiple separate 2D or 3D ultrasound images for acommon or different view windows. Optionally, the ultrasound exam mayinclude collection of one or more cine loops of 2D or 3D ultrasounddata. The operation, action or process may be performed while activelyscanning a patient and/or between separate scanning operations thatoccur during a single ultrasound exam. A length of time associated withreal time, and may vary based on a processing speed and/or operatingspecification (e.g., no intentional lag or delay). Real time includesupdating an ultrasound image shown on the display after each ultrasoundpulse within a scan and/or after each ultrasound scan sequence.Additionally or alternatively, ultrasound data may be stored temporarilyin memory of the medical imaging system during the ultrasound exam andprocessed in a live or off-line operation.

FIG. 1 illustrates a schematic block diagram of an embodiment of amedical imaging system 100. For example, the medical imaging system 100is shown as an ultrasound imaging system. The medical imaging system 100may include a controller circuit 102 operably coupled to a communicationcircuit 104, a display 138, a user interface 142, an ultrasound probe126, and a memory 106.

The controller circuit 102 is configured to control the operation of themedical imaging system 100. The controller circuit 102 may include oneor more processors. Optionally, the controller circuit 102 may include acentral processing unit (CPU), one or more microprocessors, a graphicsprocessing unit (GPU), or any other electronic component capable ofprocessing inputted data according to specific logical instructions.Optionally, the controller circuit 102 may include and/or represent oneor more hardware circuits or circuitry that include, are connected with,or that both include and are connected with one or more processors,controllers, and/or other hardware logic-based devices. Additionally oralternatively, the controller circuit 102 may execute instructionsstored on a tangible and non-transitory computer readable medium (e.g.,the memory 106).

The controller circuit 102 is configured to instruct the ultrasoundprobe 126 to emit successive Tx beams from a transducer array 112 duringan ultrasound exam. Echoes from the regions insonified by the Tx beamsmay be acquired by MLAs or parallel receive lines recorded by atransducer array 112 of the ultrasound probe 126. The Tx beams areconfigured to acquire ultrasound data of a region of interest (ROI) 201.The ROI 201 may represent a portion of a heart, typically covering thechambers of the heart and the myocardia or it may cover other vesselscontaining blood in motion.

The ultrasound data may represent repeated B-mode type of ultrasoundimaging data but typically clutter filtered temporally in order toenhance moving particles even if they are weak, such as blood. Forexample, the controller circuit 102 generates sub-images based on theultrasound data. The sub-images represent the ultrasound data thatincludes a speckle pattern. The controller circuit 102 may apply aclutter filtering to the speckle pattern. The clutter filtering canoccur during the beamforming and/or subsequent to the beamforming. Theclutter filtering extracts a blood component from the sub-image andcalculates a time delay between transmit and receive beamforming timedelays. The controller circuit 102 applies the time delay correction tothe speckle patter within the sub-image to enhance motion of the speckletracking. The clutter filtering may be performed on the sub-image priorto identifying the speckle tracking. The speckle pattern is used totrack the motion of the blood within the chambers of the heart or othervessels of interest, but it may also be used to track moving tissue forinstance myocardial motion of the heart. The motion of the speckles overtime are tracked by the controller circuit 102 to form a velocity field.For example, the motion of the speckles represents a velocity fieldindicative of a 2D dimensional blood velocity.

FIG. 2A illustrates an embodiment of a scan region 203. The scan region203 includes the ROI 201. The scan region 203 is subdivided into sectors210-214. Each of the sectors 210-214 overlap with at least one adjacentsector 210-214. For example, the sector 210 overlaps with the sector211, the sector 211 overlaps with sectors 210, 212, the sector 212overlaps with sectors 211, 213, the sector 213 overlaps with the sectors212, 214, and the sector 214 overlaps with the sector 213. Thecontroller circuit 102 instructs the ultrasound probe 126 to fire and/ortransmit n (e.g., more than one) a plurality of transmit (Tx) beamswithin each sector 210-214 representing different MLA groups. Forexample, the controller circuit 102 instructs the ultrasound probe 126to fire and/or transmit at least two Tx beams within each sector210-214. Additionally or alternatively, the amount of overlap shown inFIG. 2A may be different between the sectors 210-214. The receive linesin response to the Tx beam will overlap with each other as shown in FIG.2B.

FIG. 2B illustrate embodiments of acquisition frames 200, 250, 300, 350,400 of the ROI 201. Each sector 210-214 includes a corresponding atleast two successive Tx beams 205, 255, 305, 355, 405. It may be notedthat although one Tx beam is shown in FIG. 2A, at least two successiveTx beams (e.g., n successive firings by the ultrasound probe 126) arefired and/or transmitted by the ultrasound probe 126 for each of thesectors 210-214. The Tx beams 205, 255, 305, 355, 405 are configured toacquire ultrasound data for speckle tracking. For example, theultrasound probe 126 repeatedly fires (e.g., more than two) theplurality of Tx beams (e.g., the at least two successive Tx beams 205,255, 305, 355, 405) within each of the sectors 210-214. Optionally, theTx beams 205, 255, 305, 355, 405 may represent more than two successiveTx beams fired by the ultrasound probe 126 within each of the sectors210-214. The Tx beams 205, 255, 305, 355, 405 are shown laterally inFIG. 2B. The Tx beams 205, 255, 305, 355, 405 may also be transmittedradially from the ultrasound probe 126. The acquisition frames 200, 250,300, 350, 400 are subdivided into the sectors 210-214. The plurality ofTx beams 205, 255, 305, 355, 405 are successively transmitted from theultrasound probe 126 at each of the sectors 210-214. For example, thecontroller circuit 102 instructs the ultrasound probe 126 to fire atleast two successive Tx beams 205 in the sector 210 and receivesultrasound data along the receive lines 202, immediately afterwards, theultrasound probe 126 fires at least two successive Tx beams 255 in thesector 211 and receives ultrasound data along the receive lines 254,immediately afterwards, the ultrasound probe 126 fires at least twosuccessive Tx beams 305 in the sector 211 and receives ultrasound dataalong the receive lines 302. The process is repeated for all of thesectors 210-214, such that ultrasound data is acquired from all of thesectors 210-214. The movement of the speckle pattern recorded at anyplace within the MLA groups (e.g., acquisition frames 200, 250, 300,350, 400), can be detected from the ultrasound data for speckletracking.

The acquisition frames 200, 250, 300, 350, 400 include the receive lines202, 254, 302, 354, 402, respectively, generated in response to thecorresponding at least two successive Tx beams 205, 255, 305, 355, 405.It may be noted that the receive lines 202, 254, 302, 354, 402 overlapwith at least one alternative receive line 202, 254, 302, 354, 402 atthe one or more common positions. Optionally, the receive lines 202,254, 302, 354, 402 may represent multiple acquisitions within thesectors 210-214 from the at least two successive Tx beams 205, 255, 305,355, 405. As noted the sectors 210-214 overlap with at least oneadjacent sector 210-214 such that at least a portion of the MLA lines(e.g., the receive lines 202, 254, 302, 354, 402) overlap at one or morecommon positions. For example, the receive lines 202 of the sector 210overlap at common positions with the receive lines 255 of the sector211. The one or more common positions are shown as the overlap portions206, 256, 306, 356, 406 of the sectors 210-214.

Based on the ultrasound data received along the receive lines 202, 254,302, 354, 402, the controller circuit 102 estimates the velocity fieldin each region. For example, the controller circuit 102 analyzes theultrasound data acquired along the receive lines 202, 254, 302, 354, 402to identify motion (e.g., speckle tracking) in the ROI 201 locally inthe area acquired by repeated fire of each of the Tx beams 205, 255,305, 355, 405. For example, the controller circuit 102 receivesultrasound data for each of the sectors 210-214 from the receive lines202, 254, 302, 354, 402. The motion is calculated by the controllercircuit 102 for the speckle tracking is acquired from the repeatedfiring of the at least two successive Tx beams 205, 255, 305, 355, 405along each direction and/or the sector 210-214, individually. Forexample, the controller circuit 102 determines the speckle tracking fromthe ultrasound data acquired along the receive lines 202 from the atleast two successive Tx beams 205 for the sector 210. Subsequently, thecontroller circuit 102 determines the speckle tracking form theultrasound data acquired along the receive lines 254 from the at leasttwo successive Tx beams 255 for the sector 211. The speckle tracking forthe sectors 210-214 is identified by the controller circuit 102 andrepresents the 2D dimensional blood velocity. Additionally, thecontroller circuit 102 interpolates in time the velocity fields fromoverlapped receive lines 202, 254, 302, 354, 402.

The at least two successive Tx beams 205, 255-305, 355, 405 are shownbeing transmitted along different directions relative to the ultrasoundprobe 126 correspdoning to the different sectors 210-214 and/ordifferent beam axes. The controller circuit 102 interpolates thevelocity field estimated from the ultrasound data for the overlappingportions 206, 256, 306, 356, 406 of the receive lines 202, 254, 302,354, 402 based on a weighting signal.

Optionally, the controller circuit 102 may register the receive lines202, 254, 302, 354, 402 to correct for shifts in radial registration ofevents due to transmit wavefront arrival time differences relative toeach other. For example, the receive lines 202 may be shifted based ongeometrical differences caused by the transmit to receive beam distance.A focused Tx beam will produce a curved wavefront that will hitdifferent receive lines at different times depending on how far thereceive line is from the transmit beam axis (e.g., a location of the atleast two successive Tx beams 205, 255, 305, 355, 405 within the sectors210-214). The controller circuit 102 compensates the ultrasound dataradially along the receive lines 202, 254, 302, 354, 402, for the smalldelays produced by the geometrical differences. The controller circuit102 identifies one or more wavefronts in space at each receive pointalong the receive lines 202, 254, 302, 354, 402. The wavefront isindicative of when in time ultrasound data along the receive lines 202,254, 302, 354, 402 are received by the ultrasound probe 126. Thecontroller circuit 102 adjusts the one or more wavefronts of the receivelines 202, 254, 302, 354, 402 radially based on a registration model502.

A distance between the receive lines 202, 254, 302, 354, 402 and the atleast two successive Tx beams 205, 255, 305, 355, 405 may give rise to aslight misregistration of the location of the echoes (e.g., bloodparticles) in different parts of the sectors 210-215. Themisregistration is based on where the transmit beam axes is located, andis due to the different arrival times of the curved transmittedwavefront at the particular receive points at the ROI 201. Theregistration model 502 is configured to correct for the misregistration.The controller circuit 102 corrects the ultrasound data radially basedon the registration model to improve the accuracy of the velocityestimates for the speckle tracking. It may be noted that the correctionby the controller circuit 102 may occur after and/or during receivebeamforming (e.g., prior to speckle tracking data acquisition). Thecorrection by the controller circuit 102 ensures that the interpolationof multiple estimates of the velocity field described herein isoptimally aligned and have as little discrepancy as possible.

FIG. 3 illustrates an embodiment of the registration model 502 and theultrasound data of one of the receive lines 202 a. The registrationmodel 502 is based on priori information stored in the memory 106. Forexample, the priori information may represent the registration model 502of the ROI 201 at a corresponding depth and/or position of the ROI 201relative to the ultrasound probe 126. The depth scan may be based on theacquisition settings of the ultrasound probe 126 and/or a position ofthe ROI 201 within a patient. The registration model 502 includesestimations on when ultrasound data along the receive lines 202, 254,302, 354, 402 will be received by the ultrasound probe 126 relative tocorresponding Tx beams 205, 252, 305, 355, 405. The ultrasound data ofthe receive lines 202, 254, 302, 354, 402 at the common position arealigned by the controller circuit 102 based on the registration model502. The registration model 502 is configured to check for temporalsifts of the receive lines 202, 254, 302, 354, 402, such that thereceive lines 202, 254, 302, 354, 402 are corrected for each receiveline due to the curvature of the ultrasound probe 126 and/or the depthof the ROI 201. The correction of the receive lines 202, 254, 302, 354,402 compensates for the radial difference between the arrival time ofthe wavefront at the receive line locations and at the transmit beamaxes. The transmit beam axes correspond to a position of the at leasttwo successive Tx beams 205, 252, 305, 355, 405 within the sectors210-214.

The registration model 502 includes receive lines 512-518. The receivelines 512-518 are shown over time 510 with estimation on when baselinetarget points insonified by the transmit wavefronts 519-521 are receivedby the ultrasound probe 126. The estimations of when the baselinetargets are insonified by the wavefronts 519-521 are based on the depthof the sample position in the ROI 201, the distance between receive lineand transmit beam axes, and the characteristics (e.g., focus, aperture,apodization) of the transmit beam. For example, the registration model502 is shown in action at two of the points along the receive line at504 and 506. The sample locations 504 and 506 corresponds to places inthe ROI 201 that have different characteristics that affect theregistration of objects of the receive lines 512-518 in differentmanners. The registration model 502 estimates when the baseline targetsinsonified by the transmit wavefronts 519-521 of the receive lines512-518 are received by the ultrasound probe 126. For example, the timeestimates (Twf) may represent peaks of the transmit wavefronts 519-521along the receive lines 512-518 at the ultrasound probe 126.

The Twf may represent an interval for ultrasound signals to travel fromthe probe to the target sample and back to the probe 126 given theparticular transmit focal point the wavefronts is curving towards. Thearrival times are different for different receive MLA lines and thedifferences may be compensated radially to better align the recordeddata for which the velocity field is calculated.

The controller circuit 102 compares the ultrasound data from the receivelines 202, 254, 302, 354, 402 with the correction times of the Twf forthe corresponding transmit wavefronts 519-521 of the registration model502. The controller circuit 102 shifts the recorded ultrasound dataradially for the receive lines 202, 254, 302, 354, 402 based on the Twfin the registration model 502 to compensate for the curvature introducedby the curved wavefront. For example, the controller circuit 102 shiftsthe ultrasound data radially to compensate the transmit wavefronts519-521 of the registration model 502 based on the Twf. The registrationof the receive lines 202, 254, 302, 354, 402 enables the ultrasound dataat the common positions within the ROI 201 to be aligned with eachother.

For example, the receive line 202 includes two wavefronts 530, 531representing the ultrasound data acquired along the receive line 202 a.The controller circuit 102 compares a position of when the wavefronts530, 531 were received with the transmit wavefronts 519-520 of thereceive line 517. The controller circuit 102 registers the receive line202 to form the registered receive line 202 a. For example, thecontroller circuit 102 determines that the wavefront 530 is delayedrelative to the wavefront 519 by ten microseconds. The controllercircuit 102 shifts the data radially corresponding to the wavefront 530by ten microseconds to match (e.g., occur at the same time) thewavefront 519 and form the wavefront 530a. In another example, thecontroller circuit 102 determines that the wavefront 531 is receivedearlier relative to the wavefront 520. The controller circuit 102 shiftsthe data radially corresponding to the wavefront 531 to match thereceive line 517 of the registration model 502 to form the registeredultrasound data of the receive line 202 a. For example, the controllercircuit 102 shifts the wavefront 531 by ten microseconds to form thewavefront 531 a.

The controller circuit 102 identifies speckle tracking from theultrasound data based on the echoes received along the receive lines202, 254, 302, 354, 402. The controller circuit 102 identifies velocitydata from the speckle tracking, which represents displacement of bloodparticles identified in the ultrasound data between the repeated fireinto each individual direction for the plurality of Tx beams. Thecontroller circuit 102 estimates a velocity field from the velocitydata. For example, the velocity field represents the changes in echoes(e.g., representing blood particles) identified in the receive lines202, 254, 302, 354, 402 for the sectors 210-214. The controller circuit102 forms the velocity field based on a pattern formed from the velocitydata identified from the echoes. The pattern is based on the individualparticles (e.g., the echoes) that move along velocities identified bythe speckle tracking from the controller circuit 102. The pattern isdisplaced between the sectors 210-214 based on the ultrasound dataacquired from the acquisition frames 200, 250, 300, 350, 400. Thecontroller circuit 102 weights the velocity fields based on a weightingsignal 602

FIG. 4 illustrates an embodiment of the weighting signal 602 positionedrelative to a portion of the receive lines 202, 254, 302, 354, 402. Thereceive lines 202, 254, 302, 354, 402 are shown over time along avertical axis 650 based on when the at least two successive Tx beams205, 255, 305, 355, 405 were fired from the ultrasound probe 126. Thereceive lines 202, 254, 302, 354, 402 are shifted along a horizontalaxis 652 representing an angle relative to the ultrasound probe 126. Forexample, a position of the receive lines 202, 254, 302, 354, 402 alongthe axis 652 correspond to the different sectors 210-214, respectively.

The weighting signal 602 is shown as a linear weighting signal, which iscentered at the transmit beam axes (e.g., ‘T’) of the at least twosuccessive Tx beams 205, 252, 305, 352, 405. The ultrasound datareceived along the receive lines 202, 254, 302, 354, 402 is representedas ‘r’ in FIG. 4. Optionally, the weighting signal 602 may be parabolic,exponential, and/or the like centered at the transmit beam axes.Portions of the ultrasound data of the receive lines 202, 254, 302, 354,402 overlap with each other representing the overlap regions 604-607(e.g., which correspond to the overlap portions 206, 256, 306, 356,406). For example, a portion of the ultrasound data of the receive lines202 and 254 is within the overlap region 604, a portion of theultrasound data of the receive lines 254 and 302 is within the overlapregion 605, a portion of the ultrasound data of the receive lines 302and 354 is within the overlap region 606, and a portion of theultrasound data of the receive lines 354 and 402 is within the overlapregion 607. The ultrasound data of the overlap regions 604-607 representa portion of the receive lines 202, 254, 302, 354, 402 that arepositioned within the weighting signals 602 of adjacent receive lines202, 254, 302, 354, 402. The ultrasound data of the overlap regions604-607 represent the one or more common spatial positions of the ROI201 of another receive line 202, 254, 302, 354 402. The ultrasound dataof the overlap regions 604-607 represent collinear ultrasound data. Forexample, the ultrasound data within the overlap regions 604-607represents a common spatial position of the ROI 201 of the receive lines202, 254, 302, 354, 402.

The controller circuit 102 weights the velocity fields based on theweighting signal 602. The weight applied by the controller circuit 102is based on a distance from the corresponding transmit beam axes, whichis represented as a position of the at least two successive Tx beams205, 255, 305, 355, 405. The weights may represent a ratio based on aspatial distance of the ultrasound data, which corresponds to thevelocity data forming the velocity fields from the transmit beam axes.The weight values represent a portion of the weight value applied to thevelocity fields. For example only, the weight values may represent aratio of 1/16, which is reduced based on distance from the transmit beamaxis. For example, the receive lines 202, 254, 302, 354, 402 at agreater distance to the transmit beam axes should be weighted in theinterpolated output less than receive lines 202, 254, 302, 354, 402closer to the transmit beam axes with which they were recorded. It maybe noted in various embodiments the weighted ratio may represent ahigher resolution than 16 (e.g., 18, 20, 30) and/or a lower resolutionthan 16 (e.g., 6). The ultrasound data received along the receive lines202, 254, 302, 354, 402 outside of the weighting signal 602 have aweight of zero. For example, the velocity fields based on ultrasounddata outside of the weighting signal 602 is discarded by the controllercircuit 102. The discarded ultrasound data is not included in theoverlap regions 604-607. Based on the weighting signal 602, thecontroller circuit 102 forms weighted velocity fields

The controller circuit 102 interpolates the weighted velocity fields atthe common positions, which correspond to the different overlap regions604-607. For example, the controller circuit 102 configures a proximityof the transmit beam axes relative to each other. The proximity of thetransmit beam axes are configured by the controller circuit 102 suchthat at least a portion of the weighting signal 602 of the receive lines202, 254, 302, 354, 402 overlap with each other at the overlap regions604-607. For example, the controller circuit 102 configures the transmitbeam axes to be within the weighting signal 602 of one or morealternative receive lines 202, 254, 302, 354, 402, respectively, to formthe different overlap regions 604-607. The controller circuit 102interpolates the overlap regions 604-607 separately. The controllercircuit 102 interpolates the weighted velocity fields based on theweighting signal 602 and the receive lines 202, 254, 302, 354, 402. Forexample, the controller circuit 102 calculates a weighted mean for theoverlap region 604 at the common location of the receive lines 202, 254.The weighted mean represents a mean of the velocities of the velocityfields at the common positions, for example, corresponding to thedifferent overlap regions 604-607. For example, the controller circuit102 calculates the weighted mean based on the weight signal 602 at theoverlap region 604 of the weighted velocity fields, which adjusts thevelocities (e.g., direction, magnitude) of the velocity field at thecommon location. The controller circuit 102 interpolates the remainingoverlap regions 605-607, separately, by determining correspondingweighted means of the weighted velocity fields, which adjusts theweighted velocity fields at the common location. It may be noted that invarious embodiments the controller circuit 102 may configure thetransmit beam axes such that the overlap regions 604-607 do not overlapand/or transmit additional Tx beams to extend the overlap regions604-607 with respect to each other along the receive lines 202, 254,302, 354, 402.

FIG. 5 illustrates an embodiment of velocity data based on theacquisition frames 200, 250.

For example, the controller circuit 102 instructs the ultrasound probe126 to transmit at least two successive Tx beams (e.g., the Tx beam 205)at the sector 210. The controller circuit 102 receives echoes 662 alongthe receive lines 202. The echoes 662 represent blood particles acquiredfrom the at least two successive Tx beams 205 at the sector 210. Thecontroller circuit 102 receives echoes 662 along the receive lines 202,which represent displacement of the blood particles based on timedifferences between the at least two successive Tx beams 205.Successively, the controller circuit 102 instructs the ultrasound probe126 to transmit at least two successive Tx beams 255 at the sector 211.The controller circuit 102 receives echoes 664 along the receive lines254. The echoes 664 represent blood particles acquired from the at leasttwo successive Tx beams 255 at the sector 211. Based on a displacementof the echoes 664 from the time difference between the at least twosuccessive Tx beams 255, the controller circuit 102 can determinevelocity data. For example, the difference in position of the echoes662, 664 within the sectors 210-211 represent the velocities of thespeckle tracking 660. A portion 666 of the speckle tracking 660 is shownhaving a velocity having a downward and left motion. Additionally oralternatively, a portion 668 of the speckle tracking 660 is shown havinga velocity having a downward and right motion. It may be noted that thecontroller circuit 102 may instruct additional Tx beams within thesectors 210-211 than the two Tx beams 205, 255 shown in FIG. 5.

A portion 666 of the velocity data from the receive lines 202, 255overlap with each other, which corresponds to the overlap region 604(FIG. 4). The interpolation between the Tx beams 205, 255 result in aspatially smooth estimate of the velocity field for the sectors 210-211.

FIG. 6 further illustrates an embodiment of velocity fields 706, 708based on the acquisition frames 200, 250. For example, the controllercircuit 102 identifies the velocity data based on the echoes 662, 664received during the acquisition frames 200, 250 corresponding to thesectors 210-211. In connection with FIG. 5, the controller circuit 102determines velocity data from the ultrasound data received along thereceive lines 202, 254. Based on velocity data the controller circuit102 estimates the velocity fields 706, 708. For example, the velocityfield 706 represents the changes in echoes 662 (e.g., representing bloodparticles) between the at least two successive Tx beams 205. Thecontroller circuit 102 forms the velocity field 706 based on a patternformed from the velocity data identified from the echoes 662. Thepattern is based on the individual particles (e.g., the echoes 662) thatmove along velocities identified from the speckle tracking by thecontroller circuit 102. The pattern is displaced between the sectors210-211 based on the overlap between the adjacent sectors 210-211. Thepattern estimated by the controller circuit 102 is shown as the solidlines representing the velocity field 706. The controller circuit 102continues the estimation for the velocity data for the remaining sectors211-214. For example, the controller circuit 102 estimates the velocityfield 708 based on the pattern formed from the echoes 664. For example,the velocity field 708 represents the change in echoes identified fromthe velocity data at the sector 211. It may be noted that the velocityfields 706, 708 are acquired at different times.

The velocity fields 704 acquired from the sectors 210-211 prior tointerpolation by the controller circuit 102 includes a mismatch. Thereis a small transition between the velocity fields 706, 708 at the commonposition, which provides a mismatch. The transition occurs at the commonposition between the sectors 210-211, at the portion 666 and/or overlapregion 604. The controller circuit 102 avoids discontinuities byestimating a velocity field from two overlapping adjacent sectors210-211 that overlap (e.g., the sectors 210-211, the sectors 211-212).Additionally or alternatively, the controller circuit 102 may set up anoverlap between more than two adjacent sectors to interpolate and thusavoid discontinuities of a velocity field. The controller circuit 102may form a velocity field 706, 708 based on the ultrasound data acquiredwithin the sectors 210-211.

For example, the controller circuit 102 interpolates (e.g., calculationof the mean) the overlap region 604 (e.g., the portion 666), whichresults in a continuous change in the velocity field over time betweenthe Tx beams 205, 255. Additionally, the interpolation improves theestimate of the velocity field at the common positions (e.g., theportion 666) and decreases noise or uncertainty of the weighted velocitydata.

The controller circuit 102 interpolates the weighted velocity fields 704data within the portion 666 or the overlap region 604 by calculating aweighted mean (e.g., arithmetic mean, geometric mean) of the weightedvelocity fields 704. For example, the controller circuit 102 calculatesthe weighted mean of the overlap region 604 (e.g., corresponding to theportion 666) of the weighted velocity fields 704 acquired along thereceive lines 202, 254. The interpolation of the weighted velocityfields 704 of the overlap region 604 provides recordings of the velocityfield at different instances in time.

The velocity field 707 includes the interpolation of the weightedvelocity data at the common position (e.g., the portion 666, the overlapregion 604). The controller circuit 102 interpolates the velocity dataat the portion 666 and/or the overlap region 604, which adjusts aportion of the velocity fields 706, 708. For example, the interpolationby the controller circuit 102 provides a smoother transition between thevelocity fields 706, 708 acquired at the different sectors 210-211. Theadditional velocity data at the portion 666 improves the estimate anddecreases noise of the velocity field. The interpolation of the velocityfields in the overlap region provides lateral continuity of the velocityfields from the interpolation.

Returning to FIG. 1, the controller circuit 102 may be operably coupledto and/or control a communication circuit 104. The communication circuit104 is configured to receive and/or transmit information with one ormore alternative medical imaging systems, a remote server, and/or thelike along a uni-directional and/or bi-directional communication link.The remote server may represent a database that includes patientinformation, the registration model 502 of the ROI 201, remotely storedultrasound images of a patient, and/or the like. The communicationcircuit 104 may represent hardware that is used to transmit and/orreceive data along the uni-directional and/or bi-directionalcommunication link. The communication circuit 104 may include atransceiver, receiver, transceiver and/or the like and associatedcircuitry (e.g., antennas) for wired and/or wirelessly communicating(e.g., transmitting and/or receiving) with the one or more alternativemedical imaging systems, the remote server, and/or the like. Forexample, protocol firmware for transmitting and/or receiving data alongthe uni-directional and/or bi-directional communication link may bestored in the memory 106, which is accessed by the controller circuit102. The protocol firmware provides the network protocol syntax for thecontroller circuit 102 to assemble data packets, establish and/orpartition data received along the bi-directional communication links,and/or the like.

The uni-directional and/or bi-directional communication links may be awired (e.g., via a physical conductor) and/or wireless communication(e.g., utilizing radio frequency (RF)) link for exchanging data (e.g.,data packets) between the one or more alternative medical imagingsystems, the remote server, and/or the like. The bi-directionalcommunication links may be based on a customized communication protocoland/or a standard communication protocol, such as Ethernet, TCP/IP,Wi-Fi, 802.11, Bluetooth, and/or the like.

The controller circuit 102 is operably coupled to the display 138 andthe user interface 142. The display 138 may include one or more liquidcrystal displays (e.g., light emitting diode (LED) backlight), organiclight emitting diode (OLED) displays, plasma displays, CRT displays,and/or the like. The display 138 may display patient information, one ormore ultrasound images and/or videos, components of a graphical userinterface, one or more 2D, 3D, or 4D ultrasound image data sets fromultrasound data stored in the memory 106 or currently being acquired inreal-time, anatomical measurements, diagnosis, treatment information,tags, and/or the like received by the display 138 from the controllercircuit 102.

The user interface 142 controls operations of the controller circuit 102and the medical imaging system 100. The user interface 142 is configuredto receive inputs from the clinician and/or operator of the medicalimaging system 100. The user interface 142 may include a keyboard, amouse, a touchpad, one or more physical buttons, and/or the like.Optionally, the display 138 may be a touch screen display, whichincludes at least a portion of the user interface 142. For example, aportion of the user interface 142 may correspond to a graphical userinterface (GUI) generated by the controller circuit 102, which is shownon the display 138. The touch screen display can detect a presence of atouch from the operator on the display 138 and can also identify alocation of the touch with respect to a surface area of the display 138.For example, the user may select one or more user interface componentsof the GUI shown on the display by touching or making contact with thedisplay 138. The user interface components may correspond to graphicalicons, textual boxes, menu bars, and/or the like shown on the display138. The user interface components may be selected, manipulated,utilized, interacted with, and/or the like by the clinician to instructthe controller circuit 102 to perform one or more operations asdescribed herein. The touch may be applied by, for example, at least oneof an individual's hand, glove, stylus, and/or the like.

The memory 106 includes parameters, algorithms, protocols of one or moreultrasound exams, data values, and/or the like utilized by thecontroller circuit 102 to perform one or more operations describedherein. The memory 106 may be a tangible and non-transitory computerreadable medium such as flash memory, RAM, ROM, EEPROM, and/or the like.

The ultrasound probe 126 may have a transmitter 122, transmit beamformer121 and probe/SAP electronics 110. The probe/SAP electronics 110 may beused to control the switching of the transducer elements 124. Theprobe/SAP electronics 110 may also be used to group transducer elements124 into one or more sub-apertures. The ultrasound probe 126 may beconfigured to acquire ultrasound data or information from the anatomicalstructure of the patient. The ultrasound probe 126 is communicativelycoupled to the controller circuit 102 via the transmitter 122. Thetransmitter 122 transmits a signal to a transmit beamformer 121 based onacquisition settings received by the controller circuit 102. Theacquisition settings may define an amplitude, pulse width, frequency,gain setting, scan angle, power, time gain compensation (TGC),resolution, and/or the like of the ultrasonic pulses emitted by thetransducer elements 124. The transducer elements 124 emit pulsedultrasonic signals into the patient (e.g., a body). The acquisitionsettings may be defined by the user operating the user interface 142.The signal transmitted by the transmitter 122 in turn drives a pluralityof transducer elements 124 within the transducer array 112.

The transducer elements 124 emit pulsed ultrasonic signals into a body(e.g., patient) or volume corresponding to the acquisition settingsalong one or more scan planes. The ultrasonic signals may include, forexample, one or more reference pulses, imaging pulses, one or morepushing pulses (e.g., shear-waves), and/or the like. At least a portionof the pulsed ultrasonic signals backscatter from the ROI 201 to produceechoes. The echoes are delayed in time and/or frequency according to adepth or movement, and are received by the transducer elements 124within the transducer array 112. The ultrasonic signals may be used forimaging, for measuring changes in position or velocity within the ROI201, and/or for therapy, among other uses.

The transducer elements 124 convert the received echo signals intoelectrical signals, which may be received by a receiver 128. Thereceiver 128 may include one or more amplifiers, an analog to digitalconverter (ADC), and/or the like. The receiver 128 may be configured toamplify the received echo signals after proper gain compensation andconvert these received analog signals from each transducer element 124to digitized signals sampled uniformly in time. The digitized signalsrepresenting the received echoes are stored in memory 106, temporarily.The digitized signals correspond to the backscattered waves received byeach transducer element 124 at various times. After digitization, thesignals still may preserve the amplitude, frequency, phase informationof the backscatter waves.

Optionally, the controller circuit 102 may retrieve the digitizedsignals stored in the memory 106 to prepare for the beamformer processor130. For example, the controller circuit 102 may convert the digitizedsignals to baseband signals or compressing the digitized signals.

The beamformer processor 130 may include one or more processors.Optionally, the beamformer processor 130 may include a centralprocessing unit (CPU), a graphic processing unit capable of doingcalculations (GPU), one or more microprocessors, or any other electroniccomponent capable of processing inputted data according to specificlogical instructions. Additionally or alternatively, the beamformerprocessor 130 may execute instructions stored on a tangible andnon-transitory computer readable medium (e.g., the memory 106) forbeamforming calculations using any suitable beamforming method such asadaptive beamforming, synthetic transmit focus, aberration correction,synthetic aperture, clutter reduction and/or adaptive noise control,and/or the like. Optionally, the beamformer processor 130 may beintegrated with and/or a part of the controller circuit 102. Forexample, the operations described as being performed by the beamformerprocessor 130 may be configured to be performed by the controllercircuit 102.

The beamformer processor 130 performs beamforming on the digitizedsignals of transducer elements and outputs a radio frequency (RF)signal. The RF signal is then provided to an RF processor 132 thatprocesses the RF signal. The RF processor 132 may include one or moreprocessors. Optionally, the RF processor 132 may include a centralprocessing unit (CPU), a graphics processing unit (GPU), one or moremicroprocessors, or any other electronic component capable of processinginputted data according to specific logical instructions. Additionallyor alternatively, the RF processor 132 may execute instructions storedon a tangible and non-transitory computer readable medium (e.g., thememory 106). Optionally, the RF processor 132 may be integrated withand/or a part of the controller circuit 102. For example, the operationsdescribed as being performed by the RF processor 132 may be configuredto be performed by the controller circuit 102. Optionally the RF datareceived by the individual probe transducer elements or sub apertureprocessors may go through the RF processor 132 that mixes and bandpassfilters the RF data in order to produce in-phase/quadrature (IQ) dataprior to the beamforming, beamforming subsequently being performed onthese band limited data.

The RF processor 132 may generate different ultrasound imaging datatypes and/or modes (e.g., B-mode, C-mode, M-mode, speckle tracking,color Doppler (e.g., color flow, velocity/power/variance), tissueDoppler) for multiple scan planes or different scanning patterns basedon the predetermined settings of the first model. For example, the RFprocessor 132 may generate tissue Doppler data for multi-scan planes.The RF processor 132 gathers the information (e.g., IQ, B-mode, speckletracking, color Doppler, tissue Doppler, and Doppler energy information)related to multiple data slices and stores the data information, whichmay include time stamp and orientation/rotation information, in thememory 106.

Alternatively, the RF processor 132 may include a complex demodulator(not shown) that demodulates the RF signal to form IQ data pairsrepresentative of the echo signals. The RF or IQ signal data may then beprovided directly to the memory 106 for storage (e.g., temporarystorage). Optionally, the output of the beamformer processor 130 may bepassed directly to the controller circuit 102. Additionally oralternatively, the RF processor 132 may be in front of the beamformerprocessor 130, demodulating the channel data from each element or subaperture to form IQ data pairs that are beamformed and subsequentlyprocessed further into B-mode representation, color flow data or Dopplertrace data.

The controller circuit 102 may be configured to process the acquiredultrasound data (e.g., RF signal data or IQ data pairs) and prepareand/or generate frames of ultrasound image data representing theanatomical structure for display on the display 138. Acquired ultrasounddata may be processed in real-time by the controller circuit 102 duringthe ultrasound exam as the echo signals are received. Additionally oralternatively, the ultrasound data may be stored temporarily in thememory 106 during the ultrasound exam and processed in less thanreal-time in a live or off-line operation.

The memory 106 may be used for storing processed frames of acquiredultrasound data that are not scheduled to be displayed immediately or tostore post-processed images, firmware or software corresponding to, forexample, a graphical user interface, one or more default image displaysettings, programmed instructions, and/or the like. The memory 106 maystore the ultrasound images such as 3D ultrasound image data sets of theultrasound data, where such 3D ultrasound image data sets are accessedto present 2D and 3D images. For example, a 3D ultrasound image data setmay be mapped into the corresponding memory 106, as well as one or morereference planes. The processing of the ultrasound data, including theultrasound image data sets, may be based in part on user inputs, forexample, user selections received at the user interface 142.

FIG. 7 illustrates a flow chart of an embodiment of a method for speckleimaging, in accordance with an embodiment herein. The method 800, forexample, may employ structures or aspects of various embodiments (e.g.,systems and/or methods) discussed herein. In various embodiments,certain steps (or operations) may be omitted or added, certain steps maybe combined, certain steps may be performed simultaneously, certainsteps may be performed concurrently, certain steps may be split intomultiple steps, certain steps may be performed in a different order, orcertain steps or series of steps may be re-performed in an iterativefashion. It may be noted that the steps described of the method 800 maybe performed during the ultrasound exam in real-time. In variousembodiments, portions, aspects, and/or variations of the method 800 maybe used as one or more algorithms to direct hardware to perform one ormore operations described herein.

Beginning at 802, the controller circuit 102 determines a position of aplurality of Tx beams (e.g., the Tx beams 205, 255, 305, 355, 405, 455of FIG. 2). For example, the controller circuit 102 may configure theplurality of Tx beams such that at least two successive Tx beams 205,255, 305, 355, 405 are positioned within each sector 210-214. Based onthe orientation of the sectors 210-214, at least one sector 210-214overlaps at least one adjacent sector 210-214 at one or more commonpositions. For example, the at least two successive Tx beams 205, 255are fired within the sectors 210-211, respectively, resulting in thereceive lines 202, 254. The receive lines 202, 254 include a portion 666(FIGS. 5-6) that overlap with each other at the common position. Theultrasound data acquired at the portion 666 is represented as theoverlap region 604 shown in FIG. 4. Optionally, more than two successiveTx beams may be transmitted in each of the sectors 210-214.

The common position is based on an overlap position of the transmit beamaxis with respect to the sectors 210-214, which form the overlap regions604-607. For example, the controller circuit 102 fires and/or transmitsthe plurality of Tx beams within sectors 210-214 that are configuredsuch that the receive lines 202, 254, 302, 354, 402 overlap with eachother. Additionally or alternatively as shown in FIG. 4, the controllercircuit 102 may configure the plurality of Tx beams such that a distancebetween the transmit beam axes is less than the weighting signal 602.For example, the weighting signal 602 is centered at the transmit beamaxes corresponding to the position of the plurality of Tx beams withinthe sectors 210-214. For example, the controller circuit 102 may adjustpositions of the plurality of Tx beams to extend a length of the overlapregions 604-607 along the receive lines 202, 254, 302, 354, 402.Additionally or alternatively, the receive lines may be configured tonot be collinear from one section to the next (e.g., the receive beamsneed not be defined in exactly the same location in each of the sectionsas long as the spatial area they span out is overlapping). FIGS. 8illustrate an embodiment of at least one sub-image 950 based onnon-collinear ultrasound data 900. For example, the controller circuit102 configures Tx beams 902, 904 transmitted from the ultrasound probewithin the sector 212 to be displaced with respect to each other. The Txbeams 902, 904 are positioned at opposing sides of the sector 212. TheTx beam 902 receives echoes from a receive line 908, and the Tx beam 904received echoes from a receive line 910. There is an overlap 906 of thereceive lines 908, 910. For example, a spatial extension of the Tx beam902 overlaps with a spatial extension of the Tx beam 904 correspondingto the overlap 906. The controller circuit 102 can define a velocityfield at the overlap 906. For example, the controller circuit 102calculates within the sector 212 a common grid along radial beams or inCartesian pixels at which a velocity can be procured by interpolation ofthe velocity field. The controller circuit 102 identifies echoes 952representing blood particles (e.g., speckle tracking) based on the Txbeam 902, and echoes 954 representing blood particles based on the Txbeam 904. The adjustment in the echoes 952, 954 identified by thecontroller ciruct 102 forms the velocity field, which is shown in thesub-image 950. It may be noted that the controller circuit 102 may beconfigured such that more than two Tx beams of the plurality of Tx beamsdo not have overlapping receive lines.

At 804, the controller circuit 102 instructs the ultrasound probe 126 totransmit the plurality of Tx beams successively with respect to eachother. For example, the controller circuit 102 may instruct thetransmitter 122 to successively transmit the at least two successive Txbeams 205, 255, 305, 355, 405 within the sectors 210-214. The controllercircuit 102 acquires speckle tracking data from the receive lines 202,254, 302, 354, 402. For example, when the at least two successive Txbeams 205 are fired and/or transmitted by the ultrasound probe 126within the sector 210, and the ultrasound data is acquired from thereceive lines 202. After the at least two successive Tx beams 205, theultrasound probe 126 fires and/or transmits the at least two successiveTx beams 255 within the sector 211, and the ultrasound data is acquiredfrom the receive lines 254 for speckle tracking. It may be noted thatthe Tx beams 205, 255 overlap with each other at a common positionwithin the sector 210 (as shown in FIGS. 2B and 4). Optionally, thecontroller circuit 102 may instruct more than two Tx beams for each ofthe sectors 210-215. For example, the controller circuit 102 may repeatthe process a set number of times (e.g., M times) for each of thesectors 210-215.

At 806, the controller circuit 102 acquires ultrasound data from theechoes from the plurality of Tx beams. For example, the transducer array112 receives the ultrasound data along the receive lines 202, 254, 302,354, 402. The ultrasound data may be stored in the memory 106 afterbeing processed by the controller circuit 102, the beamformer processor130, the RF processor 132, and/or the like.

At 808, the controller circuit 102 shifts the ultrasound data radiallybased on a registration model (e.g., similar to the registration model502). For example, a distance between the receive lines 202, 254, 302,354, 402 and the Tx beams 205, 255, 305, 355, 405 may give rise to aslight misregistration of the location of the echoes (e.g., bloodparticles) in different parts of the sectors 210-214. Themisregistration is based on where the transmit beam axes is located, andis due to the different arrival times of the curved transmittedwavefront at the particular receive points at the ROI 201. Theregistration model is configured to correct for the misregistration. Thecontroller circuit 102 corrects the ultrasound data radially based onthe registration model to improve the accuracy of the velocity estimatesfrom the speckle tracking data. It may be noted that the correction bythe controller circuit 102 may occur after and/or during receivebeamforming (e.g., prior to speckle tracking data acquisition). Thecorrection by the controller circuit 102 ensures that the interpolationof multiple estimates of the velocity field described herein isoptimally aligned and have as little discrepancy as possible.

The correction by the controller circuit 102 represents a temporal shiftand/or compensation on when the ultrasound data is received along thereceive lines 202, 254, 302, 354, 402, 454. The registration modelincludes estimations on when ultrasound data along the receive lines202, 254, 302, 354, 402, 454 will be received by the ultrasound probe126. Optionally, the memory may include multiple registration models.For example, a depth and/or difference in position of the ROI 201between the different sectors 210-215 can be represented as differentregistration models. The memory 106 may include a first registrationmodel based on the depth and/or position of the ROI 201 of the sector210, and a second registration model based on the depth and/or positionof the ROI 201 of the sector 211

For example, the controller circuit 102 compares the one or morebaseline wavefronts of the receive lines 202 with the registrationmodel. The one or more wavefronts are indicative of the ultrasound datareceived along the receive lines 202. The controller circuit 102compares when the one or more wavefronts were received along the receivelines 202 with the one or more wavefronts defined by the registrationmodel. Based on the differences with the baseline wavefronts, thecontroller circuit 102 adjusts the one or more wavefronts of the receivelines 202 to match the one or more baseline wavefronts of the firstregistration model.

At 810, the controller circuit 102 generates at least one sub-imagebased on the collinear ultrasound data. For example, the collinearultrasound data corresponds to the overlap regions 604-607 (FIG. 4)representing the common locations of the sectors 210-214. The sub-imageis formed by the controller circuit 102 of the velocity data of theoverlap of the sectors 210-214. For example, the controller circuit 102identifies velocity data based on the speckle tracking of the ultrasounddata acquired by the receive lines 202, 254, 302, 354, 402 for theoverlap regions 604-607. Additionally or alternatively, the controllercircuit 102 may generate first and second sub-images. The first andsecond sub-image may represent alternating sectors 210-214. For example,the velocity data of the overlap regions 604-607 that form the first andsecond sub-images. For example, the first sub-image includes the suchthat the velocity data. For example, the controller circuit 102 may formthe first sub-

At 812, the controller circuit 102 estimates velocity fields based onthe speckle tracking from the ultrasound data. In connection with FIG.6, the controller circuit 102 identifies velocities based on the echoesreceived during the acquisition frames 200, 250 corresponding to thesectors 210-211. The velocities form velocity fields 706, 708. Forexample, the velocity field 706 represents the changes in echoes (e.g.,representing blood particles) identified from the receive lines 202(FIG. 2) for the sector 210. The controller circuit 102 forms thevelocity field 706 based on a pattern formed from the velocitiesidentified from the echoes. The pattern is based on the individualparticles (e.g., the echoes) that move along velocities identified forthe speckle tracking by the controller circuit 102. The pattern isdisplaced between the sector 210 based on the ultrasound data acquiredfrom the at least two successive Tx beams 205. The pattern is shown asthe solid lines representing the velocity field 706. Additionally oralternatively, the controller circuit 102 identifies additional velocityfields for the acquisition frames 250, 300, 350, 400 corresponding tothe sectors 211-214. For example, the controller circuit 102 may repeatthe process for the plurality of successive Tx beams 255, 305, 355, 405occurring within the sectors 211-214.

At 814, the controller circuit 102 weights the velocity fields based onthe weighting signals (e.g., the weighting signals 602 FIG. 6) to formthe weighted velocity fields. In connection with FIG. 4, the controllercircuit 102 illustrates an embodiment of the weighting signal 602 of aportion of the receive lines 202, 254, 302, 354, 402 of the at least twosuccessive Tx beams 205, 255, 305, 355, 405. The controller circuit 102configured the at least two successive Tx beams 205, 255, 305, 355, 405such that a portion of the receive lines 202, 254, 302, 354, 402,respectively, overlap with each other relative to the weighting signal602. The weighting signal 602 is centered at the corresponding transmitbeam axes. The transmit beam axes corresponds to a position of the atleast two successive Tx beams 205, 255, 305, 355, 405 with respect tothe sectors 210-214. The controller circuit 102 weights the velocityfields based on a position of the ultrasound data with respect to theweighting signal 602. For example, the weighting signal 602 mayrepresent a ratio based on a spatial distance of the receive lines 202,254, 302, 354, 402 from the transmit beam axes. The controller circuit102 applies the ratio to the velocity fields based on a position of theultrasound data acquired along the receive lines 202, 254, 302, 354, 402with respect to the weighting signal 602.

At 816, the controller circuit 102 identifies non-collinear ultrasounddata. The controller circuit 102 identifies the collinear ultrasounddata based on positions of the plurality of Tx beams. In connection withFIG. 8, the controller circuit 102 determines that the Tx beams 902, 904do not overlap at a common position. For example, the controller circuit102 determines that the position of the Tx beams 902, 904 are atopposing positions within the sector 212, which do not overlap at anypoint within the sector 212. Based on the position of the Tx beams 902,904, the controller circuit 102 identifies the ultrasound data acquiredalong the receive lines 908, 910 represent non-collinear ultrasounddata.

If non-collinear ultrasound data is identified, then at 818, thecontroller circuit 102 interpolates velocities estimated in the overlapregions onto a common grid. For example, there is an overlap 906 of thereceive lines 908, 910 from the Tx beams 902, 904. The controllercircuit 102 can define a velocity field at the overlap 906. For example,the controller circuit 102 calculates within the sector 212 a commongrid along radial beams or in Cartesian pixels at which a velocity canbe procured by interpolation of the velocity field. The common grid maybe aligned with the velocity fields from the at least two successive Txbeams 205, 255, 305. The controller circuit 102 adjusts the velocityfields within the sector 212 based on the measured velocities from thenon-collinear ultrasound data.

Additionally or alternatively, the plurality of Tx beams may not includecollinear ultrasound data. For example, the controller circuit 102 mayconfigured the plurality of Tx beams such that there is no overlap toform only non-collinear ultrasound data. The plurality of Tx beams aredirected to a common ROI 201, but do not acquire ultrasound data at acommon position. For example, the regions covered by the MLA group of afirst Tx beam overlaps with the region covered by the MLA group of asecond (e.g., and/or more) Tx beams, even though the individual MLAlines are not exactly aligned. The controller circuit 102 determines asub-sample accuracy for the non-collinear ultrasound data acquired bythe plurality of Tx beams. For example, the controller circuit 102generates the sub-images based on the plurality of Tx beams at overlapregions of the receive lines. The controller circuit 102 interpolatesgaps positioned between receive lines of the successive plurality of Txbeams. For example, the controller circuit 102 determines a velocityfield based on the non-collinear ultrasound data. The controller circuit102 interpolate in time the receive lines across and between theplurality of Tx beams, which represent the gaps. For example, gapsbetween the receive lines are interpolated in time by the controllercircuit 102. The controller circuit 102 by calculating a mean of theproximate non-collinear ultrasound data across and between the differentreceive lines to form the velocity field.

At 820, the controller circuit 102 interpolates the weighted velocityfields at the common position (e.g., the overlap regions 604-606 of FIG.4) to adjust a portion of the velocity fields. The controller circuit102 interpolates the weighted velocity fields within the overlap regions604-607, individually. For example, the controller circuit 102calculates the weighted mean (e.g., arithmetic mean, geometric mean) ofthe weighted ultrasound data of the receive lines 202, 254, 302, 354,402 within the different overlap regions 604-607. For example, thecontroller circuit 102 calculates the mean of the weighted ultrasounddata within the overlap region 604. The weighted mean calculated by thecontroller circuit 102 represents the interpolation of the weightedvelocity fields based on the receive lines 202, 254. For example, theweighted mean represents the arithmetic mean, the geometric mean, and/orthe like of the weighted ultrasound values of the receive lines 202, 254of the overlap region 602. In connection with FIG. 6, based on theinterpolation, the portion 666 of the velocity fields are adjusted.

At 822, the controller circuit 102 generates an image 1300 of a combinedweighted velocity field on the display 138. FIG. 9 illustrates anembodiment of the image 1300 shown on the display 138. For example, thecontroller circuit 102 combines the different velocity fieldscorresponding to the sectors 210-214. The controller circuit 102interpolates the overlap regions such that the combined velocity fieldsis continuous.

It may be noted that the various embodiments may be implemented inhardware, software or a combination thereof. The various embodimentsand/or components, for example, the modules, or components andcontrollers therein, also may be implemented as part of one or morecomputers or processors. The computer or processor may include acomputing device, an input device, a display unit and an interface, forexample, for accessing the Internet. The computer or processor mayinclude a microprocessor. The microprocessor may be connected to acommunication bus. The computer or processor may also include a memory.The memory may include Random Access Memory (RAM) and Read Only Memory(ROM). The computer or processor further may include a storage device,which may be a hard disk drive or a removable storage drive such as asolid-state drive, optical disk drive, and the like. The storage devicemay also be other similar means for loading computer programs or otherinstructions into the computer or processor.

As used herein, the term “computer,” “subsystem,” “controller circuit,”“circuit,” or “module” may include any processor-based ormicroprocessor-based system including systems using microcontrollers,reduced instruction set computers (RISC), ASICs, logic circuits, and anyother circuit or processor capable of executing the functions describedherein. The above examples are exemplary only, and are thus not intendedto limit in any way the definition and/or meaning of the term“controller circuit”.

The computer, subsystem, controller circuit, circuit execute a set ofinstructions that are stored in one or more storage elements, in orderto process input data. The storage elements may also store data or otherinformation as desired or needed. The storage element may be in the formof an information source or a physical memory element within aprocessing machine.

The set of instructions may include various commands that instruct thecomputer, subsystem, controller circuit, and/or circuit to performspecific operations such as the methods and processes of the variousembodiments. The set of instructions may be in the form of a softwareprogram. The software may be in various forms such as system software orapplication software and which may be embodied as a tangible andnon-transitory computer readable medium. Further, the software may be inthe form of a collection of separate programs or modules, a programmodule within a larger program or a portion of a program module. Thesoftware also may include modular programming in the form ofobject-oriented programming. The processing of input data by theprocessing machine may be in response to operator commands, or inresponse to results of previous processing, or in response to a requestmade by another processing machine.

As used herein, a structure, limitation, or element that is “configuredto” perform a task or operation is particularly structurally formed,constructed, or adapted in a manner corresponding to the task oroperation. For purposes of clarity and the avoidance of doubt, an objectthat is merely capable of being modified to perform the task oroperation is not “configured to” perform the task or operation as usedherein. Instead, the use of “configured to” as used herein denotesstructural adaptations or characteristics, and denotes structuralrequirements of any structure, limitation, or element that is describedas being “configured to” perform the task or operation. For example, acontroller circuit, circuit, processor, or computer that is “configuredto” perform a task or operation may be understood as being particularlystructured to perform the task or operation (e.g., having one or moreprograms or Instructions stored thereon or used in conjunction therewithtailored or intended to perform the task or operation, and/or having anarrangement of processing circuitry tailored or intended to perform thetask or operation). For the purposes of clarity and the avoidance>ofdoubt., a general purpose computer (which may become “configured to”perform the task or operation if appropriately programmed) is not“configured to” perform a task or operation unless or until specificallyprogrammed or structurally modified to perform the task or operation,

As used herein, the terms ‘ software’ and “firmware” areinterchangeable, and include any computer program stored in memory forexecution by a computer including RAM memory, ROM memory, EPROM memory,EEPROM memory, and non.-volatile RAM (NVRAM) memory. The above memorytypes are exemplary only, and are thus not limiting as to the types ofmemory usable for storage of a computer program.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above describedembodiments (and/or aspects thereof) may he used in combination witheach other. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the variousembodiments without departing from their scope. While the dimensions andtypes of materials described herein are intended to define theparameters of the various embodiments, they are no means limiting andare merely exemplary. Many other embodiments will be apparent to thoseof skill in the art upon reviewing the above description. The scope ofthe various embodiments should, therefore, be determined with referenceto the appended claims, along with the full scope of equivalents towhich such claims are entitled. In the appended claims, the terms“including” and “in which” are used as the plain-English equivalents ofthe respective terms “comprising” and “wherein.” Moreover, in thefollowing claims, the terms “first,” “second,” and “third,” etc. areused merely as labels, and are not intended to impose numericalrequirements on their objects. Further, the limitations of the followingclaims are not written in means-plus-function format and are notintended to be interpreted based on 35 U.S.C. § 112(f) unless and untilsuch claim limitations expressly use the phrase “means for” followed bya statement of function void of further structure.

This written description uses examples to disclose the variousembodiments, including the best mode, and also to enable any personskilled in the art to practice the various embodiments, including makingand using any devices or systems and performing any incorporatedmethods. The patentable scope of the various embodiments is defined bythe claims, and may include other examples that occur to those skilledin the art. Such other examples are intended to be within the scope ofthe claims if the examples have structural elements that do not differfrom the literal language of the claims, or the examples includeequivalent structural elements with insubstantial differences from theliteral language of the claims.

What is claimed is:
 1. A computer implemented method, comprising:transmitting a plurality of transmit (Tx) beams from an ultrasound probeto a region of interest (ROI), wherein the plurality of Tx beams aretransmitted successively with respect to each other, the plurality of Txbeams are configured to acquire ultrasound data for speckle tracking byrepeatedly firing the Tx beams, at least two of the plurality of Txbeams overlap at a common position; estimating velocity fields from thespeckle tracking; weighting the velocity fields based on weightingsignals to form weighted velocity fields, the weighting signal beingcentered at transmit beam axes of the plurality of Tx beams;interpolating the weighted velocity fields that overlap at the commonposition to adjust a portion of the weighted velocity fields; andgenerating an image of a combined velocity field on a display bycombining the weighted velocity fields.
 2. The computer implementedmethod of claim 1, further comprising identifying non-collinearultrasound data from the ultrasound data, generating at least onesub-image from the non-collinear ultrasound data, wherein one of thevelocity fields is estimated based on interpolating the velocitiesestimated in the overlapping regions onto a common grid and thenweighting and summing the estimated fields in an overlap region.
 3. Thecomputer implemented method of claim 1, wherein the weighting signal isa linear weighting that is centered about the transmit beam axes.
 4. Thecomputer implemented method of claim 1, wherein the interpolatingoperation includes calculating a weighted mean of the velocity fieldfrom tracked ultrasound data for receive lines that corresponds to thecommon location.
 5. The computer implemented method of claim 1, furthercomprising shifting the ultrasound data radially based on a registrationmodel independently for each sample location and for each of theplurality of Tx beams at every location.
 6. The computer implementedmethod of claim 1, wherein at least two Tx beams from the plurality ofTx beams are transmitted in a common sector.
 7. The computer implementedmethod of claim 1, further comprising determining a position of a secondtransmit beam axis of a second Tx beam from the plurality of Tx beamsrelative to a first transmit beam axis of a first Tx beam from theplurality of Tx beams with respect to the weighting signal such that aportion of the first and second Tx beams overlap at the common position.8. The computer implemented method of claim 1, wherein the velocityfields represent a pattern of velocities of speckle tracking based onthe ultrasound data.
 9. The computer implemented method of claim 1,further comprising applying clutter filtering to sub-images generatedfrom the ultrasound data for speckle tracking.
 10. A medical imagingsystem, comprising: an ultrasound probe configured to acquire ultrasounddata for speckle tracking; a display; and a controller circuitconfigured to: instruct the ultrasound probe to transmit a plurality oftransmit (Tx) beams to a region of interest (ROI), wherein the pluralityof Tx beams are transmitted successively with respect to each other, theplurality of Tx beams are configured to acquire ultrasound data forspeckle tracking by repeatedly firing along the Tx beams, at least twoof the plurality of Tx beams overlap at a common position; estimatingvelocity fields from the speckle tracking; weight the velocity fieldbased on weighting signals to form weighted velocity fields, theweighting signal being centered at transmit beam axes of the pluralityof Tx beams; interpolate the weighted velocity fields that overlap atthe common position to adjust a portion of the weighted velocity fields;; and generate an image of a combined velocity field on the display bycombining the weighted velocity fields.
 11. The medical imaging systemof claim 10, wherein the controller circuit is configured to identifynon-collinear ultrasound data from the ultrasound data, generating atleast one sub-image from the non-collinear ultrasound data, wherein atleast one of the velocity fields is estimated based on interpolating theultrasound data of the at least one sub-image with a portion of theweighted velocity field estimated from ultrasound data.
 12. The medicalimaging system of claim 10, wherein the weighting is a linear weightingthat is centered about the transmit beam axes.
 13. The medical imagingsystem of claim 10, wherein the controller circuit is configured tointerpolate by calculating a weighted mean of the weighted ultrasounddata for receive lines that corresponds to the common location.
 14. Themedical imaging system of claim 10, wherein the controller circuit isconfigured to shift the ultrasound data radially based on a registrationmodel independently for each sample and for the plurality of Tx beams atevery location.
 15. The medical imaging system of claim 10, wherein atleast two Tx beams from the plurality of Tx beams are transmitted in acommon sector.
 16. The medical imaging system of claim 10, wherein thevelocity fields represent a pattern of velocities of the ultrasounddata.
 17. The medical imaging system of claim 10, wherein the controllercircuit is configured to determine a position of a second transmit beamaxis of a second Tx beam from the plurality of Tx beams relative to afirst transmit beam axis of a first Tx beam from the plurality of Txbeams with respect to the weighting signal such that a portion of thefirst and second Tx beams overlap at the common position.
 18. Themedical imaging system of claim 10, wherein the controller circuit isconfigured apply clutter filtering to sub-images generated from theultrasound data for speckle tracking.
 19. A computer implemented method,comprising: transmitting a plurality of transmit (Tx) beams from anultrasound probe to a region of interest (ROI), wherein the plurality ofTx beams are transmitted successively with respect to each other, theplurality of Tx beams are configured to acquire ultrasound data forspeckle tracking by repeatedly firing the plurality of Tx beams, atleast two of the plurality of Tx beams overlap at a common position;estimating the velocity fields from the speckle tracking; weighting thevelocity fields based on weighting signals to form weighted velocityfields, the weighting signal being centered at transmit beam axes of theplurality of Tx beams; identifying non-collinear ultrasound data fromthe ultrasound data; identifying non-collinear ultrasound data from theultrasound data, generating at least one sub-image from thenon-collinear ultrasound data, wherein one of the velocity fields isestimated based on interpolating the velocities estimated in theoverlapping regions onto a common grid and weighting and summing theestimated fields in an overlap region with the weighted velocotiyfields; interpolating the weighted velocity fields at the commonposition to adjust a portion of the weighted velocity fields; generatingan image on a display of a combined velocity field by combining theweighted velocity fields.
 20. The computer implemented method of claim19, further comprising adjusting a position of a second transmit beamaxis of a second Tx beam from the plurality of Tx beams relative to afirst transmit beam axis of a first Tx beam from the plurality of Txbeams with respect to the weighting signals such that a portion of thefirst and second Tx beams overlap at the common position.